The use of mepiquat chloride (MC) in cotton (Gossypium hirsutum L.) cultivation has increased significantly in recent years. The use of MC, a growth regulator, results in higher precocity and lower height and consequently increases yield and reduces crop costs. The objective of this study was to evaluate the effects of nitrogen (N) and MC doses on fiber quality and cotton yield. This study was conducted during the 2012/13 and 2013/14 harvests in the experimental area of the Fundação de Apoio à Pesquisa Agropecuária de Chapadão, located in the municipality of Chapadão do Sul, MS, Brazil, at 18° 48’ 45.9” S, 52° 36’ 3” W, having an altitude of 820 m. The experimental design was a randomized blocks in a 5 × 4 factorial scheme comprised of five N doses (0, 40, 80, 120, 160 kg ha-1) and four MC doses (0, 50, 100, 150 mL ha-1) with four repetitions. Analyses of fiber quality included: length, uniformity, elongation, strength, micronaire index, reflectance, yellowing degrees and short fiber content. Regarding cotton yield, green color index (GCI), plant height at harvest time, and cotton seed yield were determined. The best results for fiber quality and productivity occurr with the application of 76.8 mL ha-1 of MC to the cotton crops when the N dose is greater than 80 kg ha-1. Increasing N doses causes an increase in cotton yield and micronaire index, but there is a decrease in fiber uniformity.

Modern agriculture seeks, through technology, to increase agricultural productivity, aiming at greater sustainability during food production. The application of vitamins meets this objective, acting as a biostimulant for different cultivation conditions. In this sense, the aim of this research is to evaluate the effect of the foliar application of nicotinamide on the soybean crop in two growing environments. The treatments were composed of the nicotinamide concentrations of 0, 100, 200, 300, 400, 500, and 600 mg L⁻¹ of water applied when the plants were at the R3 stage (beginning of pod formation), exogenously, by foliar spraying. The application of nicotinamide resulted in increases in the vegetative traits of plant height and the number of branches per plant by 9.7 and 7.8%, respectively. Regarding the productive characteristics, considering the average of the two cultivation sites, the application of the vitamin resulted in increments of about 15.62, 18.57, 20.53, 4.32, and 19.19% on the number of pods, number of grains, mass of grains per plant, mass of 1,000 grains, and yield, respectively. In this way, we conclude that nicotinamide, applied at concentrations ranging from 237.8 to 373.8 mg L⁻¹, promotes benefits to soybean growth and yield in different environments, and can be considered as a biostimulant.

In terms of land, the world area cultivated with sweet corn is approximately 1.04 million hectares. The United States of America is the country with the largest productive area of about 100,000 hectares and an average yield of 8.09 t ha^-1 (^{USDA, 2017}). The Brazilian scenario does not present great popularity for sweet corn, although edaphoclimatic conditions contribute to a productivity of more than 13.00 t ha^-1 (^{Luz et al., 2014}), the technological cultivation conditions maintain productivity below those observed in countries such as the USA, with around 17.17 t ha^-1 (^{FAO, 2018}).

Vitamin application can optimize plant growth and grain yield of rice crop due to its beneficial effect on many plant physiological characteristics. The present study was conducted to evaluate the effects of niacin and thiamin applied as seed soaking or foliar spray on the morphological and productive characteristics of upland rice crop (Oryza sativa L., cv. Primavera), grown under greenhouse conditions. The experiment was arranged in a randomized block design in a 4 x 2 factorial scheme, with four replicates. The treatments consisted of the application of vitamins (control; 200 mg L-1 thiamin; 200 mg L-1 niacin; and 100 mg L-1 thiamin + 100 mg L-1 niacin) and two application methods (seed soaking and foliar spraying). Morphological and productive characteristics of the rice plants were evaluated. The exogenous application of thiamin and niacin, regardless of the application method, has a beneficial effect on the growth of upland rice plants, but does not increase the grain yield of the crop.